1. Field of the Invention
The present invention relates to an ultrasonic surgery apparatus to be used in cataract surgery in which an opaque nucleus lentis (nucleus of a crystalline lens) caused by a cataract is subjected to ultrasonic vibrations so as to fragment and emulsify the nucleus lentis, and then the emulsified nucleus lentis is aspirated and removed so as to discharge the nucleus lentis.
2. Description of Related Art
In cataract surgery, an ultrasonic surgery apparatus is known which gives (applies) ultrasonic vibrations to a nucleus lentis using a tubular ultrasonic chip (referred to as an US chip, hereinafter) attached to a handpiece so as to fragment and emulsify the nucleus lentis, and aspirates and removes the emulsified nucleus lentis with an irrigation liquid supplied inside an eye so as to discharge the nucleus lentis. In this kind of apparatus, surgical conditions such as power (output) of the ultrasonic vibrations given to the US chip (referred to as US power, hereinafter), a pulse-duty ratio of the US power (the ratio of oscillation to intermission of the US power), and aspiration pressure are set by a switch or the like.
Hardness of the nucleus lentis differs according to the age of a patient, the progress of a cataract and the like, and individual differences exist between patients. However, conventionally, the surgery is generally performed under the same surgical conditions regardless of the hardness of the nucleus lentis. In addition, for dealing with the difference in the hardness of the nucleus lentis, the US power is controlled by depression operation of a pedal of a footswitch. Though the setting of the surgical conditions such as the US power and the pulse-duty ratio is changeable in accordance with the hardness of the nucleus lentis, judgment of the hardness of the nucleus lentis greatly depends on experience of a surgeon and is also troublesome.